Method of well casing repair



wsmn OF? 39364 9493.

Jan. 23, 1968 u. SKIPPER 33 9 METHOD OF WELL CASING REPAIR OriglnalFiled June 26, 1964 2 Sheets-Sheet 1 4/1/00 J/r/pp er INVENTOR.

ATTORNEVJ Jan. 23, 1968 u. SKIPPER METHOD OF WELL CASING REPAIR 2Sheets-Sheet 2 Original Filed June 26, 1964 IN V EN TOR.

01 0/7 j/w z oer ATTORNEYS United States Patent ABSTRACT OF THEDISCLQSURE A method of well casing repair wherein a radially expansibleresilient portion of a tool is located adjacent the hole in the casingand thereafter the expansible resilient portion is inflated by fiuidpressure to expand and set over the hole a corrugated steel liner havingan adhering and setting resin on its outer face. The method can includesealing and pressurizing the casing to locate leak- 1 age, and canprovide impressions of the casing damage to determine size andconfiguration. Repair and a quality check of the repair can beaccomplished during the same trip into the casing by expanding andsetting a patch over the casing damage, and then moving the tool andsealing and pressurizing the casing in the area of the patch.

This application is a division of application Ser. No. 378,841, filedJune 26, 1964, and entitled, Well Casing Repair, now issued as US PatentNo. 3,326,293.

Background of the invention The invention concerns a tool suitable forinsertion into a casing, such as a well casing, for locating and/ orrepairing certain types of damage in the casing, and a method by which acasing can be patched and the quality of the patch can be tested withoutwithdrawal from the casing.

Well casings, underground pipes, and pressure vessels in generalsometimes develop holes, ruptures, or other discontinuities whieh needto be repaired. The holes or ruptures can result from a number ofcauses, such as corrosion, unusual stresses, abrasive action, operationof equipment within the vessel, intentional fracturing, and the like,and the damaged area is usually not readily accessible, rendering repairdifficult.

A number of tools for locating the damaged area and for repairing thedamaged area have been proposed. For example, to locate the damagedarea, one may employ an electromagnetic inspection tool, a tool havingmechanical fingers for locating damage, a tool which obtains animpression of the damaged area in wax, rubber, or the like, or a toolwhich permits pressurization of the casing in successive portions todetermine at what point leakage occurs.

In general, after the damage is located, repair is effected by setting aliner in the casing over the damaged area. The liner is ordinarilyradially expansible to permit both insertion in the casing and settingagainst the inner wall of the casing, and can comprise such expansiblematerials as ductile metal or plastics, glass fabrics impregnated with asetting resin, or brittle materials such as steel when the brittlematerials are corrugated or otherwise shaped to permit expansion. Aliner comprising corrugated steel covered with glass fabric and asetting resin has been found to be particularly effective for repairingdamage when the liner must withstand high pressures and stresses, suchas in well casings. Tools for setting a liner generally comprise,depending on the type of liner, of course, either a means forlongitudinally compressing at least a portion of the liner to expand theliner radially and set it against the casing, resilient means forradially expanding against the liner to expand and set the liner, or asolid cone-shaped expander which is drawn through the liner to expand itradially.

Summary of the invention The invention provides a novel tool which canbe employed not only to set a radially expansible liner in a casing orother object but also to locate a damaged area in a casing or otherobject, and which can exhibit a variety of desirable characteristics aswill be pointed out hereinafter. The invention also provides a novelmethod which can reduce the amount of the work involved in repairing adamaged area in a casing or other object.

In general, a tool exemplifying one embodiment of the invention, whichis suitable for insertion into an object and then expansion against ortoward its interior by fluid pressure, comprises an outer sleeve havinga radially expansible resilient portion between its ends, an innersleeve slidable in the outer sleeve to two positions, and transverseconduit means and sealing means associated With the inner and outersleeves in a number and in places sufficient for permitting in one ofthe two positions fluid from Within the inner sleeve to flow through aconduit means to the interior or inside of the resilient portion andexpand this portion, and for permitting in the other of the twopositions fluid near or against the resilient portion to flow back intothe inner sleeve to deflate the resilient portion and fluid in the innersleeve to flow therefrom to the outside of the tool. The transverseconduit means and sealing means together constitute what in general maybe referred to simply as conduit means for permitting the above fluidflows in the two positions.

Thus, when the tool is attached to a string of pipe and then insertedinto a casing, the resilient portion of the tool can be expanded orinflated by injection of fluid under pressure through the string of pipeinto the inner sleeve, and deflation can be accomplished by adjusting bymanip ulation of the string of pipe the relative position of the innerand outer sleeve, whereby fluid near the resilient portion and in theinner sleeve can flow to the outside of the tool. In the latterposition, fluid in the string of pipe and in the inner sleeve can bedisplaced out into the casing, thereby keeping fluid away from anoperator of the tool at the open end of the casing as the tool andstring of pipe are withdrawn.

The above tool can be easily modified to gain a number of additionalcharacteristics which are desirable especially with respect to therepair of casings in oil or gas wells. For example, suflicient conduitmeans and sealing means may be added to permit pressurization of thecasing at one end of the tool by fluid flowing out of the inner sleevewhen the resilient portion is expanded, thereby permitting adetermination of leakage through the casing above or below the tool.Conduit means and sealing means may also be located to permitequalization of pressures in the casing above and below the tool whenthe resilient portion of the tool is expanded. This characteristics isdesirable, for example, when the flow and pressure of oil or gas withina casing are strong enough to interfere with the setting of a liner inthe casing.

In general, the method of the invention for patching a hole in a casingand then testing the quality of the patch comprises placing anexpansible patch or liner around a radially expansible resilient portionof a tool having means for permitting fluid pressure to expand theresilient portion, attaching the tool to a pipe String and inserting aportion, moving the tool to a position away from but near the patch,such as, for example, immediately below the patch in a well casing,injecting fluid into the tool to inflate the resilient portion againstthe casing wall, injecting fluid into the section of casing containingthe patch, and determining whether leakage occurs. The patchingoperation can then be completed by decreasing the fluid pressure on theresilient portion of the tool to deflate this portion and thenWithdrawing the tool from the casing. Thus, in accordance with thismethod, a casing can be patched and the quality of the patch can betested during the same trip into the casing.

Brief description of the drawings In the drawings:

FIGURE 1 is a sectional view of a tool in accordance with the inventionpositioned in a well casing with a liner disposed adjacent a damagedarea of the casing;

FIGURE 2 is a sectional view taken along the line 22 in FIGURE 1;

FIGURE 3 is a schematic illustration of a guide slot employed in theembodiment of the invention shown in FIGURE 1;

FIGURE 4 is a sectional view of the central portion of the tool ofFIGURE 1 illustrating one operating position of the tool;

FIGURE 5 is a sectional view illustrating more of the portion of thetool of FIGURE 1 in a second operating position;

FIGURE 6 is a sectional view of a central portion of the tool of FIGURE1 illustrating a third operating position of the tool.

FIGURE 7 is a sectional view of a central portion of the tool of FIGURE1 illustrating a fourth operating position of the tool.

For purposes of clarity, the presence of fluid is not illustrated in thedrawings, although its flow is indicated.

Description of the preferred embodiments The invention will be betterunderstood by reference to the drawing wherein FIGURE 1 is a verticalsectional view illustrating a preferred embodiment of a tool inaccordance with the invention. The tool there shown comprises an outersleeve 16 and an inner sleeve 12 slidable in the outer sleeve 10. Thesleeve has a radially expansible resilient portion 14 between its endsaround which i disposed a liner 16 for patching a discontinuity such asa hole 18 in a well casing 20. The outer sleeve 10 comprises twononexpansible sections and a section of a resilient material, theresilient portion 14, mounted hermetically between and with twononexpansible sections. The resilient material may be any suitablematerial, such as natural or synthetic rubber, neoprene, and the like,and can be reinforced, if necessary, with cord, braided wire, or othermaterial to withstand the pressure required to complete the patchingoperation. Further, the resilient portion 14 may comprise a plurality oflayers of resilient material with a reinforcing material such as wirebetween adjacent layers. The resilient material may be connected to thenonexpansible sections in any suitable manner, such as with bondingagents, mechanical means such as metal bands 21, or a combination of thetwo. The inner sleeve 12 and the nonexpansible sections of the outersleeve 10 are preferably made of steel, but obviously may be constructedof other suitable materials.

Near the ends of the resilient portion 14 and between the inner sleeve12 and the outer sleeve 19 are sealing or packing means 22 and 24, suchas an O-ring or other annular packing member made of, for example,neoprene, natural or synthetic rubber, or other suitable packingmaterial. Sealing means 26, 28, and 30 which can be similar inconstruction to the sealing means 22 and 24 are spaced in order belowthe sealing means 24 and between the inner sleeve 12 and the outersleeve 10. All of the sealing means can be held in place by retaininggrooves in the inside wall of the outer sleeve 10 as shown, or by othersuitable retaining means.

A pair of transverse ports or apertures 32 and 34 are longitudinallyspaced in the inner sleeve 12, and a pair of transverse ports orapertures 36 and 38 in the outer sleeve 10 are spaced longitudinallyabout the same distance apart as the ports 32 and 34. At the bottom endof the inner sleeve 12 is a means 40 for closing this end when the innersleeve 12 contains fluid under pressure, which means may be apermanently closed portion of the inner sleeve 12, but which preferablyis a check valve comprising a ball 42 resting on a seat 44. A checkvalve at this point permits fluid in the casing 20 to enter into theinner sleeve 12 and then flow out the top of the tool as the tool islowered in the casing 20 when it is full of fluid, thereby permittingeasy descent of entry into the casing 20.

Connected to the bottom end of the outer sleeve 10 is preferably a plug46 which protects the remaining portions of the tool from injury duringentry into the casing 20 and which has centralizing means 48 to helpcenter the tool in the casing 29. The centralizing means 48 preferablycomprises a plurality of fins having frangible portions which will breakif the tool sticks in the casing 20, such as when the liner 16 is onlypartially expanded but yet firmly fixed against the casing 20. Thecentralized means 48 may be located on the outer sleeve 10, but ispreferably located on an easily replaceable part, such as the plug 46,in case of breakage. An aperture 50 is preferably provided in the plug46 to permit fluid in the casing 29 to reach the mean 40 for closing theinner sleeve 12 during descent of the tool.

As better shown in FIGURE 2, the liner 16 is preferably a corrugatedsteel tube which is expansible to set against the casing 20,particularly when the liner 16 must withstand high pressures andstresses. The outside surface of the liner 16 is preferably coated withglass fabric and a setting resin to help effect a good seal with thecasing 20, and the outside surface of the liner 16 preferably has aperimeter equal to or slightly greater than the internal circumferenceof the casing 20 to ensure a tight fit.

The preferred tool also comprises a means for positioning or locatingthe inner sleeve 12 relative to the outer sleeve 19. Such means may takethe form of a pin or member extending from one of the sleeves 10 and 12and slidable in one or more slots in the wall of the other of thesleeves 10 and 12 or possibly take the form of a wormand-rackarrangement. The means preferably comprises a pair of pins 54 and 56which protrude from sleeve 12 and are slidably disposed in opposed slots58 and 60 in the interior wall of the outer sleeve 10. The pins 54 and56 can be an integral part of the inner sleeve 12, although separatepins permit easier assembly of the tool.

As shown schematically in FIGURE 3, the slots 58 and 60 preferably forma part of identical slot tracks, only one of which, track 61, isillustrated in FIGURE 3. The slot tracks may assume a variety ofconfigurations depending on the number of relative positions between theinner sleeve 12 and the outer sleeve 10 which may be desired. The slottrack 61 as shown preferably comprises the slot 58 disposedlongitudinally, a second longitudinal slot 62, a third longitudinal slot64, and two interconnecting slots 66 and 68, slot 66 being shown inFIGURE 1. Thus, the slot track 61 has four positions A, B, C, and D towhich the pin 54 can slide, and the inner sleeve 12 can assumecorresponding positions A, B, C and D relative to the outer sleeve 10.The slot 60 in FIGURE 1 is associated with an identical but oppositelydisposed slot track.

Detents 70 and 72 pivotally mounted on the outer sleeve 10 by pins 74and 76 are spring-biased against the inner sleeve 12 by tension springs78 and 80, and engage a collet or shoulder 82 on the inner sleeve 12 tokeep the pins 54 and 56 and the inner sleeve 12 in position A untildetents 70 and 72 are forcibly disengaged. Obviously, only one detent isrequired to accomplish the intended purpose, but

one or more pairs of detents are preferred to maintain alignment of thesleeves and 12. The detents 70 and 72 and the collet 82 are preferablyshaped to require more force to disengage them than to engage them.

At the top end of the inner sleeve 12 is a means 84 for attaching theinner sleeve 12 to a pipe 86, preferably threads mateable with threadson the pipe 86. Also near the top end of the tool may be located acentralizing means 88 which can be constructed much the same as thecentralizing means 48 near the bottom of the tool.

FIGURE 1 illustrates the tool with the inner sleeve 12 positioned withrespect to the outer sleeve 10 when pins 54 and 56 are in position A.This is the relative position normally maintained while the tooldescends in the casing and the liner 16 is centered over the hole 18-.In this position the detents 70 and 72 are engaged with the collet 82and keep the outside sleeve 10 from changing position with respect tothe inner sleeve 12. When the tool is located properly in the casing 20,fluid under pressure, preferably water or a drilling mud, is injectedinto the open end of pipe 86 or its extension from which it flows intoinner sleeve 12, closing the check valve at the bottom end of the innersleeve 12 and flowing into the interior of the resilient portion 14through port 32. As particularly illustrated in FIGURE 4, wherein arrowsrepresent the direction of flow, the resilient portion 14 consequentlyexpands out towards the casing 20 and sets the liner 16 against thecasing 20. Flow through the port 34 is prevented or checked during thisperiod by the pair of sealing means 28 and 30.

If pressures in the casing 20 above and below the expanded resilientportion 14 need to be equalized at this time, the inner sleeve 12 ismoved relative to the outer sleeve 10 to position B, as shown in FIGURE5, by raising the pipe 86 or its extension the required distance andforcibly overriding the action of the detents 70 and 72 against thecollet 82. The outer sleeve 10 does not move :because of frictionbetween the expanded resilient portion 14, the liner 16, and the casing20. In this position, the port 32 passes above the sealing means 22 andcommunicates with the aperture 36 in the outer sleeve 10 as well as anyspace open to the outside of the tool between the inner sleeve 12 andthe outer sleeve 10, and the port 34 falls between the sealing means 26and 28 and communicates with the aperture 38 in the outer sleeve 10.Thus, the resilient portion 14 remains expanded, and pressures in thecasing 20 above and below the resilient portion 14 can equalize by flowin either direction along the path indicated by the arrows.

When the liner 16 is permanently set in the casing 20 and theeffectiveness of the liner 16 is to be tested, the pipe 86 is loweredcausing the inner sleeve 12 to return to position A and to be latched inthis position by detents 70 and 72 and collet 82, the position shown inFIGURE 1. The pressure of the fluid in the pipe 86 and the inner sleeve12 is then decreased to deflate the resilient portion 14, and the toolwithout the liner 16 is moved to a position in the casing 20 below theliner 16, as shown in FIGURE 6, where the resilient portion 14 is againinflated according to the procedures described in the discussion aboutposition A shown in FIGURES 1 and 4. The inner sleeve 12 is then movedto position C relative to outer sleeve 10 by raising the pipe 86 andoverriding the detents 70 and 72, rotating the pipe 86 to move the pin54 through the interconnecting slot 66 and the pin 56 through itscorresponding slot, and then raising the pipe 86 until the pins 54 and56 and the inner sleeve 12 are in position C. In this position, as shownin FIGURE 6 wherein the arrows indicate the direction of fluid flow, theport 34 is between a pair of sealing means 24 and 26 and thus blocked,and the port 32 is in a position Where fluid introduced into the innersleeve 12 by way of the pipe 86 will flow out of the tool throughaperture 36 and the open space between the upper ends of the innersleeve 12 and the outer sleeve 10, and pressurize the section of thecasing 20 containing the liner 16 as a patch, thereby allowing adetermination of any leakage past the liner 16.

To remove the tool from the casing 20 while emptying the fluid contentsof the pipe 86 and the inner sleeve 12, the pins 54 and 56 aremanipulated through their corresponding slot tracks to position D bymanipulation of the pipe 86 while the resilient portion 14 is expanded.As shown in FIGURE 7, in position D the port 34 communicates with theinterior of the resilient portion 14 and the port 32 communicates withthe outside of the tool through the aperture 36 and the open spacebetween the inner sleeve 12 and the outer sleeve 10. As shown by thearrows in FIGURE 7, fluid adjacent the resilient portion flows into theinner sleeve 12 to deflate the resilient portion 14, and fluid in theinner sleeve 12, including fluid entering the inner sleeve 12 from thepipe 86 as the tool is raised, flows to the outside of the tool.

Thus, a preferred embodiment of the tool of the invention permits one topatch a casing and test the quality of the patch during the same tripinto the casing. The tool also is capable of emptying its fluid contentsto its outside during removal of the tool from the casing, therebyavoiding troublesome conditions near the operator removing the tool fromthe casing.

The tool can also be employed in accordance with the above procedures toget an impression of a damaged area in a casing by having animpressionable material on the outside of the resilient portion, andthen expanding the resilient portion against the damaged area. A sleeveof cured rubber with an outside covering of uncured rubber strapped overthe resilient portion is particularly suitable to obtain an impression.Wax, metal foil, or similar material coated over the resilient portioncan also be employed if conditions are such that the impressionablematerial will not be washed or dissolved from the resilient portion.

A damaged area in a casing can be located with a tool in accordance withthe invention by inflating the tool at successive places in the casing,pressurizing the casing at one end of the tool at each of the places,and determining between which places leakage occurs by detectingpressure drop in the casing. For example, by inflating the resilientportion at intervals of one hundred feet and pressurizing the casingabove the tool at each place, it can be determined within which intervala leak exists. By then pressurizing and testing the casing at differentplaces along this interval the leak can be located with sufficientaccuracy to permit patching. Of course, different size intervals may bechosen for testing as suits the operator of the tool.

I claim:

1. A method for patching a hole in the wall of a casing and testing thequality of the patch during the same trip into the casing, which methodcomprises placing an expansible patch around a radially expansibleresilient portion of a tool having means therein for permitting fluidpressure to expand said resilient portion; attaching said tool to a pipestring and inserting said tool in said casing to a place where saidexpansible patch is substantially centered over said hole;

injecting fluid into said tool to inflate said resilient portion andthereby to expand and set said patch against said casing over said hole;

decreasing fluid pressure on said resilient portion to deflate saidportion;

moving said tool to a position away from but near said patch;

injecting fluid into said tool to inflate said resilient portion againstthe wall of said casing;

injecting fluid into the section of said casing containing said patchand determining whether leakage occurs;

decreasing fluid pressure on said resilient portion to deflate saidportion; and

withdrawing said tool from said casing.

2. The method described in claim 1, wherein casing fluid is passedthrough said tool into said pipe string during insertion of the toolinto the casing to decrease resistance to the passage of said 'tool andto equalize the pressure within said tool with the pressure of saidcasing fluid.

3. The method described in claim 1, wherein said fluid injected intosaid tool is drained into said casing during withdrawal of said toolfrom said casing.

4. The method described in claim 1, wherein during the setting of saidpatch the fluid pressure in the casing immediately below said patch ismaintained substantially equal with the fluid pressure in the casingimmediately above said patch.

5. The method described in claim 1, wherein:

casing fluid is passed through said tool into said pipe string duringinsertion of the tool into the casing to decrease resistance to thepassage of said tool and to equalize the pressure within said tool withthe pressure of said casing fluid;

during the setting of said patch the fluid pressure in the casingimmediately below said patch is maintained substantially equal with thefluid pressure in the casing immediately above said patch; and

said fluid injected into said tool is drained into said casing duringwithdrawal of said tool from said casing.

6. A method for repairing a hole in the wall of a casing comprisingplacing an impressionable material around a radially expansibleresilient portion of a tool having means therein for permitting fluidpressure to expand said resilient portion; attaching said tool to a pipestring and inserting said tool in said casing to a place where saidimpressionable material is substantially centered over said hole;

injecting fluid into said tool to inflate said resilient portion andthereby expand said impressionable material against said hole to make animage of said hole on said material;

decreasing fluid pressure on said resilient portion to deflate saidportion and withdrawing said tool from said casing;

subsequently placing an expansible patch around a radially expansibleresilient portion of a tool having means therein for permitting fluidpressure to expand said resilient portion; attaching said tool to a pipestring and inserting said tool in said casing to a place where saidexpansible patch is substantially centered over said hole;

injecting fluid into said tool to inflate said resilient portion andthereby to expand and set said patch against said casing over said hole;

decreasing fluid pressure on said resilient portion to deflate saidportion;

moving said tool to a position away from but near said patch;

injecting fluid into said tool to inflate said resilient portion againstthe wall of said casing;

injecting fluid into the section of said casing containing said patch topressurize said casing section and to determine whether leakage occurs;

decreasing fluid pressure on said resilient portion to deflate saidportion; and

withdrawing said tool from said casing.

7. A method for repairing a hole in the wall of a casing comprisingattaching to a pipe string a tool having a radially expansible resilientportion and a means therein for permitting fluid pressure to expand saidresilient portion;

inserting said tool in said casing to a predetermined location;

injecting fluid into said tool to inflate said resilient portion andthereby expand said portion into sealing contact with the walls of saidcasing;

injecting fluid into the sealed section of said casing to pressurizesaid casing section and to determine whether leakage occurs within saidpressurized section;

decreasing fluid pressure on said resilient portion to deflate saidportion;

moving said tool to another predetermined location and repeating theinflation of said resilient portion of said tool and the pressurizationof said casing section to determine whether leakage occurs;

repeating the steps of inflation of said resilient portion of said tooland pressurization of the casing section until leakage is located;

decreasing fluid pressure on said resilient portion to deflate saidportion and withdrawing said tool from said casing;

subsequently placing an impressionable material around a radiallyexpansible resilient portion of a tool having means therein forpermitting fluid pressure to expand said resilient portion;

attaching said tool to a pipe string and inserting said tool in saidcasing to a place where said impressionable material is substantiallycentered over said hole;

injecting fluid into said tool to inflate said resilient portion andthereby expand said impressionable material against said hole to make animage of saidholeum on said mtaerial;

decreasing fluid pressure on said resilient portion to deflate saidportion and withdrawing said tool from said casing;

subsequently placing an expansible patch around a radially expansibleresilient portion of a tool having means therein for permitting fluidpressure to expand said resilient portion;

attaching said tool to a pipe string and inserting said tool in saidcasin to a place where said expansible patch is substantially centeredover said hole;

injecting fluid into said tool to inflate said resilient portion andthereby to expand and set said patch against said casing over said hole;

decreasing fluid pressure on said resilient portion to deflate saidportion;

moving said tool to a position away from but near said patch;

injecting fluid into said tool to inflate said resilient portion againstthe wall of said casing;

injecting fluid into the section of said casing containing said patch topressurize said casing section and to determine whether leakage occurs;

decre zg vig'fluid p'ressure on said resilient portion to deflate saidportion; and

withdrawing said tool from said casing.

References Cited UNITED STATES PATENTS CHARLES E. OCONNELL, PrimaryExaminer.

DAVID H. BROWN, Examiner.

